Microstructural control of Nb addition in nanocrystalline hard magnets with different Nd content

The effects of Nb addition on the hard magnetic properties and microstructure evolution in Nd/sub 8/Fe/sub 78-x/Co/sub 8/B/sub 6/Nb/sub x/ and Nd/sub 12/Fe/sub 82-x/B/sub 6/Nb/sub x/ nanocrystalline alloys are presented. Low Nd containing alloys consist of (alpha)-Fe and Nd/sub 2/Fe/sub 14/B phases. The Nd/sub 12/Fe/sub 80.5/B/sub 6/Nb/sub 1.5/ alloy probably contains NbFeB phase besides the (alpha)-Fe and Nd/sub 2/Fe/sub 14/B phases. It is found that Nb atoms tend to enrich at grain boundary regions, resulting in refined microstructure and significantly improved coercivity over a range of conventional Nd-Fe-B alloys.